Set data type

 Set data type:

It is a collection of elements of different datatypes without duplicate elements where order is not important.

Examples:

1. Set is Unordered List

>>> s={10,20,30,"Hello"}

>>> type(s)

<class 'set'>

>>> print(s)

{'Hello', 10, 20, 30}

(or)
s=set([10,20,30]) # create

2. Set may contain different data  types

>>> a={10,2.5,True,3+4j,’Ram’}

>>> type(a)

<class 'set'>

>>> print(a)

{True, 2.5, 10, 'Ram', (3+4j)}

3. Since it unordered list so index concept is not available and slicing operation is also not available

>>> s={10,30,50}

>>> s[0]=20 #error

>>> s[1:3] #error there is no slicing   operation since index is not available

4. Dynamically grow able

>>> s={10,20,False,2.3}

>>> s.add(40)

>>> print(s)

{False, 40, 2.3, 10, 20}

>>> s.remove(2.3)

>>> print(s)

{False, 40, 10, 20} 

5. Duplication is not allowed

>>> s={'h','e','l','l','o','o'}

>>> print(s)

{'o', 'e', 'l', 'h'}

By using del keyword we can delete entire set

Ex:

s={'h','e','l','l','o','o'}

>>> del s

>>> print(s) #it is deleted entire set

Assignments:

1. Which of the following is not the correct syntax for creating a set? 
a)    set([[1,2],[3,4]])
b)    set([1,2,2,3,4])
c)    set((1,2,3,4))
d)    {1,2,3,4}

Answer: a

2. Which of the following statements is used to create an empty set? 
a)   { }
b)   set()
c)   [ ].
d)   ( )
Answer: b

Explanation: { } creates a dictionary not a set. Only set() creates an empty set. 

3. What is the output of the following piece of code when executed in the python shell? 
>>> a={5,4}
>>> b={1,2,4,5}
>>> a<b
a)   {1,2}
b)   True
c)   False
d)   Invalid operation

Answer: b
Explanation: a<b returns True if a is a proper subset of b

4. If a={5,6,7,8}, which of the following statements is false? 
a)   print(len(a))
b)   print(min(a))
c)   a.remove(5)
d)   a[2]=45

Answer: d
Explanation: The members of a set can be accessed by their index values since the elements of the set are unordered. 

5. If a={5,6,7}, what happens when a.add(5) is executed? 
a)   a={5,5,6,7}
b)   a={5,6,7}
c)   Error as there is no add function for set data type
d)   Error as 5 already exists in the set 
Answer: b

Explanation: There exists add method for set data type. However 5 isn’t added again as set consists of only non-duplicate elements and 5 already exists in the set. Execute in python shell to verify.

Click here to see related videos

Net topic         : frozenset datatype

Previous Topic: Tuple
Assignment 4